In general, an endoscope has a flexible insertion portion to be inserted into a sample to, for example, observe and treat a lesion in the sample, and an operation portion to perform operations to curve the insertion portion in four directions (U-direction, D-direction, R-direction, and L-direction). The operation portion has a UD angle knob to perform the operations in the U-direction and the D-direction, and an RL angle knob to perform the operations in the R-direction and the L-direction. When the lesion is, for example, observed and treated, the UD angle knob and the RL angle knob are properly operated so that the insertion portion can be curved in the U-direction, the D-direction, the R-direction, and the L-direction.
There is another endoscope which drives a motor to rotate a curving portion in the U-direction, the D-direction, the R-direction, and the L-direction.
For example, an endoscope according to International Publication No. 2012/074013 enables a manual operation to be performed to curve a curving portion of an insertion portion in the upward (U) direction and the downward (D) direction, and enables an automatic operation to be performed by the driving of a motor to curve the curving portion in the leftward (L) direction and the rightward (R) direction. An operation portion is provided with a knob to be operated to curve the curving portion in the upward (U) direction and the downward (D) direction, and a dial to be operated to curve the curving portion in the leftward (L) direction and the rightward (R) direction.